Authored By:
Ricky Bennett, Rich Lieske
Lu-Con Technologies
Flemington, New Jersey
Corey Beech
RiverBend Electronics
Rushford, Minnesota
Summary
For centuries, the squeegee blade has been used throughout many applications for depositing viscous materials through screens and stencils to transfer images on to substrates, from cloth material to electronic circuit boards. One area of blade printing mechanics that have been reviewed many times is the angle of attack of the blade. Typically it has been tested from 45 degrees to 60 degrees to optimize the printing quality and efficiency. However, this typically ends up as a compromise, from fill characteristics (45 degrees) to print definition (60 degrees).
This paper will present the revolutionary performance of the profiled squeegee blade, which has recently been developed to create a virtual multi angle of attack for unsurpassed process control for all types of stencil printing processes.
Conclusions
With today's production challenges with finer pitch devices and lead free processes, there is a strong desire for innovative solutions towards the improvement in paste roll control. Various attempts with coating of blades have not yielded the desired effect of minimizing the paste starving concern with lead free processes. In conjunction with paste roll control, enhanced paste deposition for lower area ratio apertures is not a desire but a requirement.
The profiled squeegee blade fulfills the dynamics of paste roll control and aperture fill by its unique shape by controlling the mass of paste from wicking up the blade face. In conjunction to the paste mass control, the unique profile design channels the paste in to a smaller bead under the profile and thereby creating a localized controlled paste flow.
Initially Published in the IPC Proceedings
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